I'm trying to sharpen the saw about airport classifications as it relates to handle CAT I, II, III approaches and how it relates to aircraft, pilot or possibly air traffic controller certifications to land at any given airport.

My understanding of the three categories are equipment based such as NAVAIDS aircraft use to land at any given airport and not so much experience or certification required to land the aircraft.

For example if a airport is certified by the FAA as CAT II, does this mean the airport cannot land CAT III equipped aircraft?

No, Cat III certified aircraft can land at Cat I, II, and III approach (also airports without ILS) provided that the crew are trained for that type of approach and a few other restrictions.

An aircraft that is certified only to Cat I cannot land using a Cat III approach however runways with Cat III are usually backwards compatible ie a Cat III approach is usually also a Cat I and II approach with higher minima's etc.

The airport, the aircraft and the pilots must be certified to make the landing.

If an airport R/W is certified for CAT III, Obviously the aircraft must be CAT III Capable, and the pilots must be certified for CAT III ops. I mention the pilots ONLY because in RARE circumstances you can have a new Capt. with less than 100 hrs (IIRC) of CAT III training/experience and the landing cannot be attempted. (That was the policy where I used to work). It is rare in that I had only come across this twice in my 20yrs at the airline.

If an airport is certified for CAT II, and weather is CAT III, the airport is closed, or at least that R/W is closed. Does not matter that the aircraft is CAT III capable.

Quoting GentFromAlaska (Thread starter):My understanding of the three categories are equipment based such as NAVAIDS aircraft use to land at any given airport and not so much experience or certification required to land the aircraft.

For the runway and aircraft, it's an equipment issue. For the crew, it's a training issue (which will involve some experience in a simulator). For all three, it's a certification issue. The equipment must be certified and the pilots' training must be certified.

Quoting GentFromAlaska (Thread starter):For example if a airport is certified by the FAA as CAT II, does this mean the airport cannot land CAT III equipped aircraft?

No. Just because an aircraft is CatIII equipped does not mean that it is necessarily using that capability. It can still do CatII or CatI approaches just fine.

Quoting MSYPI7185 (Reply 2):If an airport is certified for CAT II, and weather is CAT III, the airport is closed, or at least that R/W is closed. Does not matter that the aircraft is CAT III capable.

The airport and runway don't have to be closed. They can stay open - it's just that nobody can legally land on them. People could still take off on the runway if they wanted to (and if their weather minimums were met).

Quoting Mir (Reply 3):The airport and runway don't have to be closed. They can stay open

All true. In fact weather conditions rarely require the airport operator (only folks who close runways/airports) to close a runway other than for snow removal or similar, even having a vehicle doing a runway check for braking action rarely closes the runway.

Any views shared are strictly my own and do not a represent those of any former employer.

Quoting EMBQA (Reply 5):.....and the mechanic that last released the aircraft from maintenance...!!! It requires a special training class and certification to return a CAT I /II / III aircraft back to service.

For DL that isn't quite the case. A mechanic only needs to be Autoland qualed on that aircraft to sign for autoland write ups and test check outs. The actual release from mtc can be signed by any release qualified mechanic. A mechanic without the autoland qual can even work on the system, but only a qualified mechanic can recertify the system for Autoland.

Quoting FLY2HMO (Reply 7):Meaning that, (in the US at least) if operating under part 91, you can legally take off with zero ceiling and zero visibility. Not that I'd recommend it.

Nor would I. But it is legal to do, so if someone calls up for takeoff with CatIIIb weather, the tower has no reason to refuse them the clearance (as long as the runway is clear, no other conflicting traffic, etc., of course).

Quoting FLY2HMO (Reply 7):Common sense would dictate that you wouldn't want to take off in any WX conditions worse than the approach with the highest minima at the airport you're departing from.

Quoting Zkpilot (Reply 1):An aircraft that is certified only to Cat I cannot land using a Cat III approach however runways with Cat III are usually backwards compatible ie a Cat III approach is usually also a Cat I and II approach with higher minima's etc.

Backwards compatible? You make it sound like cat III equipment is to blu-ray as cat II is to DVD.

Categorisation in this context merely reflects the maximum (or minimum in this case I suppose) capabilities of the equipment and crew. A cat III ILS is capable of meeting the standards for precision and integrity of signal required for cat III operations. Clearly then, it is inherently capable of meeting the standards for cat II and cat I precision as well.